Swimming, soaking in a spa, whirlpool, hot tub or hydrotherapy pool, can promote an individual""s health and relieve physical and psychological stresses. Swimming pools, hot tubs, spas, hydrotherapy pools and the like, referred to collectively as xe2x80x9cpoolsxe2x80x9d, must be kept clean in terms of water quality. The elimination of dirt, debris, hair, oils, and microorganisms from the pool water is critical towards ensuring the health and safety of the individual bathing in the pool. This can be particularly true with indoor pools which are generally heated and are supposed to be used in all seasons. Sweat, hair and other foreign matter originating from the human body are potential sources of bacterial growth that can contaminate the pool water and deteriorate its quality.
To eliminate contaminants, pool water has traditionally been treated by continuous passage of a portion of the water from the pool over filters containing sand or over filters containing diatomaceous earth, after a first passage through a filter for the removal of materials such as, particulates, dirt, debris, insects, hair, oils, etc. The water is then returned to the pool with, optionally, the addition of a chemical product such as chlorine, chlorine dioxide, bromine, iodine, ozone or the like, in order to disinfect it.
Sand and diatomaceous earth are typically the filtration media of choice, but are not the only filtration media currently available. Substitutes for sand and/or diatomaceous earth include ceramic filters and activated carbon. For example, porous ceramic filters have a three-dimensional network of extremely fine filtering spaces that can trap organic matter, such as oils. However, these ceramic filters can become easily clogged with the build-up of oils, dirt and biofilm formed by microorganisms associated with the flora of a typical pool environment.
More importantly, the first filter often used for the filtration of pool water is often found as a filtration cartridge mounted in combination with a water suction and delivery system. The coarsely filtered water can then be filtered through a secondary system, if present, as described above. The filter cartridges are generally made of a pleated polyester fabric arranged radially along the generating lines of a central cylinder. The base of the cartridge is placed in communication with the suction system in order to filter the water that enters from the outside of the cartridge and passes across its walls. Although the polyester fabric filter removes contaminants, it gets dirty quite quickly from the build up of oils, microorganisms and biofilm, and it is often difficult to clean due to its fragile construction. Consequently, cleansing of the filter can be problematic, not easily lending itself to decontamination and removal of microorganisms. Cleaning of the filter can lead to tearing of the polyester, degradation of the porosity of the material and/or further embedding the debris into the polyester fabric.
Therefore, a need exists which overcomes one or more of the above identified problems.
The present invention circumvents one or more of the problems described above by providing a nonwoven or carded nonwoven, e.g., a composite, which retains particles, oils, eliminates bacteria, and withstands pool environments without the release of the antibacterial, if present in the composite, into the pool water. The present invention also pertains to methods of use of the nonwoven or carded nonwoven filter media as pool filters or in filter cartridges and also kits which include the filter media.
The filter media of the invention is inexpensive and readily manufactured. Additionally, the fibrous materials used for the filter media are commercially available, thereby providing flexibility in the processing of various grades of the filter media, e.g., basis weight, thickness, etc.
In one aspect, the invention pertains to nonwoven filter media which include one or more layers of core-sheath fibers. Preferably, the nonwoven filter media is carded. The sheath portion of a fiber is bonded to one or more adjacent core fibers, forming an interconnected three-dimensional array of core fibers interspersed and connected by the sheath material. The sheath material connects the core fibers together, such that the nonwoven filter media, e.g., carded nonwoven media, is porous. This bonding is generally accomplished by melting the sheath material about the core fiber. At points of contact, the melted sheath material solidifies upon cooling, thereby forming the interconnected three-dimensional porous filter media.
In another aspect, the invention pertains to antimicrobial nonwoven filter media, that includes an antimicrobial fiber and a second fiber, wherein the antimicrobial fiber and second fiber are entangled together. In a preferred embodiment, the second fiber is a core-sheath fiber which forms an interconnected three-dimensional array of core fibers and antimicrobial fibers interspersed and connected by the sheath material. The sheath material connects the core fibers and antimicrobial fibers together, such that the nonwoven filter media is porous. In a preferred embodiment, the antimicrobial fibers and second fibers, e.g., core-sheath fibers, are carded. This results in a carded nonwoven filter material.
The filter media of the invention advantageously has excellent physical characteristics, such as stiffness, which allows for ease in pleatability. As a consequence, the filter media readily lends itself to manufacturing procedures which require that the media be pleated every inch, returning, for example, at 180 degree angles without loss in mechanical strength or integrity. This physical and mechanical qualities of the present filter media provide that an increased number of pleats can be used in the construction of a filter cartridge. The increase in the number of pleats is directly proportional to increased surface area of a filter cartridge. Therefore, the surface area provided by the filter media of the invention allows for increased filtration efficiency of oils, dirt, debris, microorganisms (and their biofilm) and the like from water, air, or body fluids.
The filter media of the invention can advantageously be used for filtration of public water supplies, home tap water, and, preferably, pools. In a preferred embodiment, the filter media of the invention are used in pools for the removal of oils, dirt, debris and microorganisms. The filter media can be configured in a filter cartridge or other configurations known in the art that are readily adapted to the final application. In some instances, layers of sheets of the filter media of the invention, stacked on one another, is a suitable method for the clarification/purification of water.
The filter media composites of the present invention can be used in a variety of filtration applications beyond water purification. The filter media of the invention can also advantageously be used for the filtration of air to remove air-borne particulates and/or microorganisms. Among the uses for such filter media are industrial face masks, ASHRAE filters, HEPA filters, e.g., HEPA vacuum filter bags, and ULPA filters.
Other advantages of the invention will be readily apparent to one having ordinary skill in the art upon reading the following description.
All percentages by weight identified herein are based on the total weight of the nonwoven layer unless otherwise indicated.